1. Field of the Invention
This invention relates generally to Satellite Positioning Systems (SATPS) and in particular to Multi-Function Satellite Positioning Systems (MSATPS) and related methods.
2. Related Art
SATPS were created using standalone receivers to aid with navigation. SATPS receivers have become commonplace and have been connected to a number of different wireless devices, such as cellular telephones, Personal Communication System (PCS) receivers, Personal Digital Assistants (PDA), and wired devices such as a Personal Computer (PC).
There has been increased interest in integrating SATPS with cellular telephony system since the Federal Communications Commission (FCC) passed regulations requiring that cellular telephones to be locatable within 20 feet when an emergency call, such as a “911” call (also referred to as Enhanced 911 or “E911”), is placed by a given cellular telephone. Such position data can assist police, paramedics, and other law enforcement or public service personnel, as well as other agencies seeking to determine the position of a particular wireless communicator such as a cellular telephone.
Previous approaches to SATPS receivers have included general digital signal processors (DSPs) that are used to process positioning signals. Such implementations are used for stand-alone GPS receivers. One such approach is described in U.S. Pat. No. 5,812,087 issued on Sep. 22, 1998. In that approach, a general purpose programmable digital signal chip is used to process signals received from a GPS antenna or a communication antenna. The general purpose programmable DSP is dedicated to processing the signals received by the two antennas. Similarly, U.S. Pat. No. 5,781,156, issued on Jul. 14, 1998 also describes a GPS receiver that has a general purpose programmable DSP.
Another approach to implementing a SATPS receiver is described in U.S. Pat. No. 5,945,944 issued on Aug. 31, 1999 and is a continuation-in-part of application Ser. No. 08/842,559. In that patent, a combined GPS receiver that has both a GPS receiver and a communication receiver is described as having a DSP that is shared by both a GPS system and the communication system, further a microprocessor receives signal data from the digital processor. Thus, both a microprocessor and a DSP are required for the combined GPS receiver.
A general purpose programmable DSP is different from a general purpose processor or controller. A digital signal processor is defined in Newton's Telecom Dictionary, 19th Edition, March 2003, as:                “A digital signal processor is a specialized semiconductor device or specialized core in a semiconductor device that processes very efficiently and in real time a stream of digital data that is sampled from analog signals ranging from voice, audio and video and from cellular and wireless to radio and television. As opposed to a general-purpose processor, a DSP is often designed to solve specific processing problems. A DSP architectures focuses on algorithmic efficiency and may use an instruction set that is more or less tailored toward the problem the DSP is solving. General purpose processors, on the other hand, may sacrifice algorithmic efficiency for general-purpose capability and push clock-speed to achieve performance. A DSP typically has much greater mathematical computational abilities than a standard microprocessor. In some applications, like wireless, PDAs and cell phones, constraints on power consumption require performance improvements other than faster clock speed. In other applications, like cellular base stations and high definition TV, where the number of channels or the high data rate require signal processing capabilities an order of magnitude greater than general purpose processors, a DSP that uses processing parallelism can provide much higher performance much more efficiently than even the fastest general-purpose processor. A DSP often performs calculations on digitized signals that were originally analog (e.g. voice or video) and then sends the results on. There are two main advantages of DSPs—first, they have powerful mathematical computational abilities, more than normal computer microprocessors. DSPs need to have heavy mathematical computation skills because manipulating analog signals requires it. The second advantage of a DSP lies in the programmability of digital microprocessors. Just as digital microprocessors have operating systems, so DSPs have their very own operating systems. DSPs are used extensively in telecommunications for tasks such as echo cancellation, call progress monitoring, voice processing and for the compression of voice and video signals as well as new telecommunications applications such as wireless LANs and next-generation cellular data and cellular internet services. They are also used in devices from fetal monitors, to anti-skid brakes, seismic and vibration sensing gadgets, super-sensitive hearing aids, multimedia presentations and desktop fax machines. DSPs are replacing the dedicated chipsets in modems and fax machines with programmable modules—which, form one minute to another, can become a fax machine, a modem, a teleconferencing device, an answering machine, a voice digitizer and device to store voice one a hard disk, to a proprietary electronic phone. DSP chips and DSP cores in custom chips are already doing for the telecom industry what the general purpose microprocessor (e.g. Intel's Pentium) did for the personal computer industry. DSP chips are made by Analog Devices, AT&T, Motorola, NEC and Texas Instruments, among others. DSP cores are made by BOPS, DSP Group, Infineon and others.”Thus, DSPs are different from microprocessors and are tailored for processing specific real time data.        
Known limitation exists in current implementations. For example, an integrated or sensor solution results in an impact on the limited processing power of cellular telephone (even if a digital signal processor is used, an engine solution results in an increase drain on the power of a device. The limited processing power may also result in a longer period for satellite acquisitions and a more limited dynamic range. Further, the additional processing requirements of a SATPS receiver also may affect the performance of the cellular telephone and other devices incorporating SATPS receiver.
Therefore, there is a need for methods and systems for a SATPS receiver for utilization in cellular telephones and other devices that overcomes the disadvantages set forth above and others previously experienced.